Biliary and pancreatic cancers often are diagnosed when the patient presents specific symptoms characteristic of a blockage of either the patient's bile and/or pancreatic duct, such as jaundice. Typically, by the time symptoms appear in the patient, a tumor in the bile or pancreatic duct is at an advanced stage and is therefore inoperable. As a result, management of the cancer usually focuses on palliation of the symptoms. As an alternative to surgical bypass procedures for palliation, a stent or endoprosthesis may be positioned through the obstructed area (stricture) so as to maintain a pathway for fluid flow.
Typically, stents used for drainage in the biliary tract are nonexpandable tubular structures formed from biocompatible polymers. Before endoscopic placement of a biliary or pancreatic stent, endoscopic retrograde cholangiopancreatography (ERCP) may be performed to evaluate the biliary tree and the pancreatic duct. Preferably, the location, length, and proximal extent of the stricture are determined, and a stent of an appropriate length is selected for deployment into the duct. Because a fluoroscopic projection of the duct shows detail in only two dimensions, however, and the duct extends along three dimensions, it may be difficult for the clinician to accurately assess the stent length needed for placement into the duct.
To deploy the stent, a wire guide may be passed into the duct and across the stricture, and the stent may be advanced over the wire guide and into the duct of interest. A distal end of the stent may be directed across the ductal obstruction, while a proximal end of the stent remains proximal of the stricture, preferably protruding into the duodenum.
In some cases, it may be desirable or necessary to place more than one stent at the obstructed site to expand the stricture commensurate with the diameter of the duct. Accordingly, once the first stent is placed, a second stent may be introduced into the patient and delivered using the same procedure. After placement of the second stent, additional stents may be separately introduced into the patient and delivered to the treatment site in order to open the obstructed region to the desired diameter. Depending on the size of the duct and the diameter of the stents, it may be necessary to place two to six stents across the obstructed region.
The process of delivering and deploying multiple stents into the pancreatic or bile duct can be tedious and slow. It would be desirable to have a system and method that allowed for more efficient placement of multiple stents. It would also be beneficial if fewer stents were needed to open larger diameter ducts. In addition, it would be advantageous if a clinician could more accurately assess the stent length needed for placement into the duct.